Obtaining and analyzing samples of fluid from subsurface reservoir formations is often conducted during oil and gas exploration. Such operations are hindered by the harsh subterranean environment specific to oilfields, including high temperature and pressure (HPHT), corrosive fluids, and severely constrained geometry. The difficulty in acquiring and performing measurements on fluidic samples in such an environment are further complicated by use of electronic sensors that typically require power, monitoring and/or telemetry.
Several oil-field related operations, such as fracturing a geological formation, would greatly benefit from the capability of producing a map of the subterranean fracture geometry, and of the fracture evolution in time. Such capability does not currently exist. A similar need exists for a technology which can be used in monitoring and performing fracture analysis of subterranean carbon dioxide sequestration reservoirs.
Measurements of fluid properties and composition far from an oil well are difficult to perform in the oilfield environment. The capability to inject very small sensing devices far into a geological formation by use of a Proppant or similar means of sensor transport, and to be able to determine their position and the precise moment when they perform a measurement or acquire a sample would greatly benefit the industry.
Measurements need to be performed in other types of high-pressure situations, where the deployment of active sensing systems with on-board electronics and data transmission capabilities may either be impossible due to environmental issues (for example temperatures and pressures that are too high) or may prove to be too expensive to justify economically. Typical examples involve measurements within aquifers, portable water wells, or in a submarine environment. Such an environment may be a lake, or a sea or ocean.
Often there is a need for injecting, or liberating, small particles or small amounts of chemicals at predefined times into a remote environment, or into an environment which is difficult to access. Such small particles or chemicals may be used as tracers, may participate in chemical reactions, or may be used as pharmaceuticals. Exemplary environments where such particles, chemicals, or pharmaceuticals may be injected include without limitation oil and water reservoirs, pre-existing or induced fractures within such reservoirs or within other geological formations, oil, water and/or gas wells, water bodies such as lakes, rivers and oceans, or a human body.
Monitoring of hazardous waste disposal reservoirs and of adjacent aquifers for contamination mapping and leaching is also a very important domain, where the need for miniaturized and economical sensing solutions is prominent.